[5] pry(main)> require 'matrix'
=> true
[6] pry(main)> a = Matrix[[1, 1], [1, 1]]
=> Matrix[[1, 1], [1, 1]]
[7] pry(main)> b = Matrix[[2, 2], [2, 2]]
=> Matrix[[2, 2], [2, 2]]
[8] pry(main)> a + b
=> Matrix[[3, 3], [3, 3]]
[9] pry(main)> a * b
=> Matrix[[4, 4], [4, 4]]